Vitro evolution in microfluidic systems

Abstract

The invention describes a method for isolating one or more genetic elements encoding a gene product having a desired activity, comprising the steps of: (a) compartmentalising genetic elements into microcapsules; and (b) sorting the genetic elements which express the gene product having the desired activity; wherein at least one step is under microfluidic control. The invention enables the in vitro evolution of nucleic acids and proteins by repeated mutagenesis and iterative applications of the method of the invention.

The invention claimed is: 
     
       1. A method for providing a library of entities, comprising the steps of:
 producing a plurality of aqueous droplets by partitioning an aqueous fluid as it is flowing through a channel with an immiscible continuous phase that comprises a fluorinated oil and a fluorinated polymer surfactant, each droplet comprising at least one entity; and 
 pooling the droplets into one or more common compartments that have larger cross-sectional areas than the channel that slows the velocity of the droplets as compared to their velocity within the channel, wherein the droplets contact each other but do not fuse within the one or more common compartments, thereby providing a library of encapsulated entities. 
 
     
     
       2. The method of  claim 1 , wherein the entities are nucleic acids, proteins, or cells. 
     
     
       3. The method of  claim 2 , wherein the nucleic acids are primers for a polymerase chain reaction (PCR). 
     
     
       4. The method of  claim 1 , wherein the entities are labeled. 
     
     
       5. The method of  claim 4 , wherein the entities are optically labeled. 
     
     
       6. The method of  claim 1 , wherein the entities are fluorescently labeled antibodies. 
     
     
       7. The method of  claim 1 , wherein the entities are chemically labeled antibodies. 
     
     
       8. The method of  claim 1 , wherein the droplets are unable to fuse due to the presence of a surfactant. 
     
     
       9. The method of  claim 1 , wherein the droplets are separated by the immiscible continuous phase in the channel. 
     
     
       10. The method of  claim 1 , wherein the oil is a perfluorinated oil. 
     
     
       11. The method of  claim 1 , wherein the droplets are monodisperse with respect to each other.